Not sure if anyone mentioned this or not. Go to a "good" bike shop, not Wally World, K-Mart and talk to the guys there. They will show you how to properly use the gears which can make a BIG difference in your ride. You will really enjoy riding once you know a little more about it. Always wear a helmet and gloves and you might even want to get some good cycling shorts and a jersey once you get your mileage up, those can make a big difference too. I didn't start riding until I was 45 years old - ten years ago. I still don't go that far, usually 25 - 35 miles, the most I have ever done is 67. Riding with someone that is at your ability is always great. You will be amazed at how quickly you learn and really start to enjoy and look forward to riding.
Have fun and keep those pedals turning!!!